1. Field of the Invention
The present invention relates to an image supply device such as a digital camera or a digital-camera-equipped cellular phone, a printing apparatus, and a printing system.
2. Description of the Related Art
In recent years, digital cameras, digital-camera-equipped cellular phones, and portable terminals capable of capturing an image by a simple operation and converting the obtained image into digital image data are widely used. To print a photo from an image captured by such a camera, normally, a personal computer (PC) receives the obtained digital image data from the camera, processes the data, and then outputs it to a color printer for printing. Recently, color printing systems (to be referred to as “direct printing” hereinafter) capable of transmitting digital image data directly from a camera to a color printer and printing it without an intervening PC are employed. See, e.g., Japanese Patent Laid-Open No. 11-112932. So-called photo-direct (PD) printers are also commercially available, which can directly load a memory card mounted in a camera to store captured images and print image data stored in the memory card.
Direct printing was previously a model-dependent print function, which only could be implemented between cameras and printers of the same maker. However, recent standardization in the industry is making the environment ripe for direct printing between cameras and printers of different makers. For example, PictBridge that is officially placed in the public domain by CIPA is a representative standard of direct printing between products of different makers. The PictBridge aimed mainly at wired connection via USB at first. However, products adaptable to wireless connection using TCP/IP have also been available lately.
Requirements for print functions implemented by direct printing are wide-ranging. For example, the demand is growing not only for a function of printing an image captured by a camera on a paper sheet, like a silver halide photo, but also for a function of printing an image together with a mail document, a document created by a wordprocessor, or a document with a complex layout such as a Web page. A print function using an XHTML document on a BPP protocol in Bluetooth® is an example of a technique of meeting this requirement.
As described above, the environment is becoming ripe for standardization of interface specifications and multifunctional equipment in direct printing. However, conventional direct printing aims at simple photo printing like a silver halide photo. The function is insufficient for printing a document including text information or a document with a complex layout such as a Web page. In addition, the conventional direct printing system has no means for exchanging detailed information representing the XHTML support state.
A printer that supports XHTML can receive and print an XHTML file without any problem. However, some printers do not offer full support because of restrictions on the ROM or RAM capacity or CPU performance. In this case, the camera must convert print data in accordance with the support state of the printer. For example, if a printer supports “mime multiplex” of XHTML, the camera encrypts image data, embeds it in an XHTML file, and transmits it to the printer. If a printer supports “print by reference”, the camera describes the storage location of image data in an XHTML file as URI and transmits it to the printer. In this case, in case of necessity, the printer requests the image data of the camera by using the URI. That is, a printer must notify an image supply device such as a camera of its XHTML function support state.
To implement maker-independent XHTML printing, at least one of a camera and a printer must acquire its partner's capability information (to be referred to as Capability hereinafter) representing whether the partner has a function of interpreting XHTML. The conventional direct printing system has only a command to send Capability from a printer to a camera by one-way communication. It is impossible to send Capability from a camera to a printer.
The conventional system has trouble if a plurality of printers as connection targets exist around a camera. For example, assume that a user wants a camera to connect only to a printer supporting XHTML. The camera can acquire the Capability of each printer only when connection is established according to a predetermined communication protocol. Hence, icons representing completion of connection are displayed on both the camera and printer. The user may believe a printer to support XHTML even when it does not.
When a printer supports only “print by reference”, the camera describes the storage location of image data in an XHTML file as URI and transmits it, as described above. In the conventional direct printing system, the printer that requests the camera to transfer image data must designate it as a file ID of PTP because the transport layer uses PTP. Hence, the camera must notify the printer in advance of link information between the file ID of PTP and the URI as the image data storage location in the camera.